How do I use try_emplace and insert_or_assign with std::map?

In C++, the `std::map` container provides several methods for inserting or updating elements. Two useful methods introduced in C++17 are `try_emplace` and `insert_or_assign`. Here's an overview of how to use these methods:

Using try_emplace

The `try_emplace` method constructs an element in-place if the key does not already exist in the map. If the key already exists, the method does not alter the map.

Using insert_or_assign

The `insert_or_assign` method either inserts a new element or updates the value of an existing key in the map. If the key is already present, its value is updated; otherwise, a new key-value pair is added.

Example


        #include <iostream>
        #include <map>

        int main() {
            std::map myMap;

            // Using try_emplace
            myMap.try_emplace(1, "One");
            myMap.try_emplace(1, "Uno"); // Does not insert, as key '1' already exists

            // Using insert_or_assign
            myMap.insert_or_assign(2, "Two");
            myMap.insert_or_assign(2, "Dos"); // Updates value for key '2'

            // Print the map contents
            for (const auto& pair : myMap) {
                std::cout << pair.first << ": " << pair.second << std::endl;
            }

            return 0;
        }

C++ std::map try_emplace insert_or_assign C++17 key-value pairs map operations

How do I use try_emplace and insert_or_assign with std::map?

Using try_emplace

Using insert_or_assign

Example

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How do I use try_emplace and insert_or_assign with std::map?

Using try_emplace

Using insert_or_assign

Example

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Popular Topics

Recent Languages